I'm hoping to figure out the make/model so I can find keys to remove the upper housing and get it working as a home extension.
Protel or Elcotel is my best guess, as to the model, you may have to open it to verify.
But I'm sure theres others here who will know right off.
Just drill a small hole above the lock and punch out the arm. It is a GTE quadrum housing and can have any kind of locks, Medeco, Abloy, etc. You will never find keys for it.
Looks like Abloy. Yes, drill center hole.